1. Field of the Invention
The present invention relates to a video recording apparatus such as a video camera, and more specifically to a video recording apparatus suitable for providing a slow motion effect or a quick motion effect in a movie by digitally, instead of using a film, converting the frame-rate, and a multiplexing method, a picture encoding method, a program, and a recording medium used for configuring the video recording apparatus.
2. Related Art of the Invention
Conventionally, movies have been taken and edited with a film. Conventional film based video recording apparatus provides a slow motion effect or a quick motion effect in a movie by changing a recording frame-rate with fast forwarding or slow playing of the film.
The advance of semiconductor technology, computer technology, and high-density recording technology has boosted picture quality and performance of a broadcasting apparatus system. Now, more and more movies are being produced with a digital cinema system using a VTR and a computer-based non-linear editing facility. Such new methods include a method for digitally providing a slow motion effect and a quick motion effect with a multi-frame-rate capable imaging device that can set a frame-rate at imaging to any value by controlling a CCD (Charge Coupled Device) driving method in an imaging part.
For example, “TECHNIQUE CALLED ‘VARIABLE FRAME RATE FUNCTION’” Shashin-Kogyou Publishing Inc. by Katsuyuki Taguchi and Minoru Namikawa, “video α” 2003, April, vol. 19/No. 4, serial number 180 describes a VTR that can digitally provide a slow motion effect and a quick motion effect with a multi-frame-rate capable imaging device. This device can vary a frame-rate by one frame/second from four frames/second to 60 frames/second to progressively drive a CCD. For simplicity, an imaging frame-rate is X frames/second and a picture signal output from a CCD is called an Xp picture signal in the description later. Although a frame-rate can vary by one frame/second in the example of “TECHNIQUE CALLED ‘VARIABLE FRAME RATE FUNCTION’”, X needs not be an integer and can be set any number in the range of real numbers.
A CCD output is Xp picture signals. The signals varied to 60 frames/second by so-called pull-down process, which repeats each frame for once or more times, is recorded as 60p picture signals in VTR part included in a multi-frame-rate capable imaging device. A VTR using so-called intra-frame compression, in which compression is completed for each frame, is used for a VTR here so as to retrieve any frame in compressed video data.
That is to say, the multi-frame-rate capable imaging device is provided with a view-finder including a liquid crystal panel called EVF (Electronic View Finder). The EVF can typically display only 60p picture signals and cannot display picture signals at the frame-rate as it shot, for example, at 12 frames/second. Xp picture signals have to be subjected to a pull-down process to be 60p picture signals, which can be displayed on EVF, so that EVF can display Xp picture signals of a CCD output display. 60p picture signals resulted from the pull-down process is recorded on a VTR.
At playing, 60p picture signals resulted from the pull-down process is played from the tape. Conventional video recording apparatus provide a slow motion effect and a quick motion effect by retrieving Xp picture signals, the signals before the pull-down process, from the 60p picture signals and changing its time axis to make the frame-rate 24 frames/second with a special device called “frame-rate converter”, and recording the signals as 24p picture signals in a VTR for editing.